<!doctype html>
<html>
<head>
<meta charset="utf-8">
<title>无标题文档</title>
<style>
	.dabox{width:500px;height:400px; background:#ff0; margin:0 auto;}
	.top{width:100px; height:50px; background:#f00;}
	.bottom_l{width:200px; height:50px; background:#0f0; }
	.bottom_r{width:100px;height:50px; background:#00f; float:right;}
</style>
</head>

<body>
<div class="dabox">
	<div class="top"></div>
    <div class="bottom_l"></div>
    <div class="bottom_r"></div>
</div>
</body>
</html>
